bugGNU Octave - Bugs: bug #38134, [octave forge] (signal) bug in...


bug #38134: [octave forge] (signal) bug in remez

Submitter:  CarnĂ« Draug <carandraug>
Submitted:  Mon 21 Jan 2013 03:22:30 PM UTC
Category:  Octave Forge Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Fixed Assigned to:  None
Originator Name:  Open/Closed:  * Closed
Release:  * dev Operating System:  * Any
Fixed Release:  None Planned Release:  None
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Fri 30 Jul 2021 08:33:54 PM UTC, comment #2: 

it appears that the remez function has been significantly reworked since this report was made. the original failing result no longer runs in that calling format (weights need to be applied before the FTYPE 'differentiator' call). This also applies to the file #32732 patch, which contains tests that cannot be run as they currently stand. the ones from textbooks that do run appear to produce the correct output).

bug should probably be closed.

Nicholas Jankowski <nrjank>
Project Member
Fri 21 Jun 2013 03:37:59 AM UTC, comment #1: 

Confirmed that the remez() function does give poor results for the given example, although I don't see exactly the same coefficients as reported.

Mike Miller <mtmiller>
Project Administrator
Mon 21 Jan 2013 03:22:30 PM UTC, original submission:  

The following was reported on the mailing list on 15/01/2012 by Anders Brandt. nabble thread.

I am experiencing problems with the remez command in Octave 3.2.4 on Windows. I have tried a number of different orders and griddensities, but all seem to give error. I am trying to define a differentiator.


B=remez(4,[0 0.8],[0 0.8]*pi,'differentiator',4*1024) gives me coefficients
  -0.02488   0.35098  -1.00103   0.00000 ... (neg. symmetry)

MATLAB's firpm, which I understand should give the same (similar) output, gives

B=  0.1519   -0.4161    0.9424         0

The MATLAB result is a really decent differentiator, which cannot be said about the remez output.

Robert T. Short commented:

I don't think this function works.  I have not tried it in a long time, but I never got any useful results. I played around with it enough to believe it would not be hard to fix, but it has never bubbled up the priority stack enough to actually do it.


Carnë Draug <carandraug>
Project Member


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Attach Files:

Attached Files
file #32732:  Bug38134.patch added by laurentg (14KiB - application/octet-stream - See Bug38134.patch for a fix attempt (including tests against other sources I could find))


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -email is unavailable- added by siko1056 (Updated the item)
  • -email is unavailable- added by nrjank (Posted a comment)
  • -email is unavailable- added by jwe (Updated the item)
  • -email is unavailable- added by laurentg (Updated the item)
  • -email is unavailable- added by carandraug (original bug reporter)

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    Follow 9 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2021-08-25 siko1056 StatusConfirmed Fixed
        Open/ClosedOpen Closed
    2019-02-27 mtmiller Carbon-CopyRemoved 80942 -
    2017-08-13 jwe Summarysignal package: bug in remez [octave forge] (signal) bug in remez
    2014-12-30 carandraug Carbon-CopyRemoved 79703 -
    2014-12-30 laurentg Attached File- Added Bug38134.patch, #32732
    2013-06-21 mtmiller StatusNone Confirmed
        Operating SystemMicrosoft Windows Any
    2013-01-21 carandraug Carbon-Copy- Added -email is unavailable-

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